Panels made in metal case with bench support and the electrical scheme on the front panel.   The board must consist of a complete Modulator / Transmitter / Receiver / Demodulator chain, programmable to operate with pulse width modulation or pulse position modulation. Technical features: The board must include the signal and timing generator and a testing tone generator, so that it is possible to perform even complex exercises with a minimal help from external equipment. Sampling frequency variable with continuity around 8 kHz. Band of the input analogue signal: from 340 to 3400 Hz. The panel must contain the elements that are necessary to carry out, with suitable, connections, a PWM modulation/demodulation system and a PPM modulation/demodulation system. The panel must complete of timing generator necessary for the operation of the circuits and of auxiliary devices that make the use of the panel itself simple and rational. These auxiliary devices consist in a test sinusoidal tone generator with fixed frequency and variable amplitude and in a simulator of transmissive medium equipped with a generator of artificial noise, adjustable in amplitude to allow a realistic experimentation. The panel must plan according to rigorous standard for what concerns the safety of people and of the equipment itself. For what concerns the protection of the circuits against the wrong connections and the overloads, that the panel shall be  protected against accidental inversions of the supply and against short-circuits towards ground of the measure terminals. With this panel it must be possible to perform the following exercises: PWM and PPM modulation and demodulation procedure, Performance of PWM and PPM systems with respect to the transmission quality in presence of disturbances, attenuation and noise, Relationship between transmitted signal band and sampling frequency; considerations on the band occupied by the modulated signal, Study of the PWM modulator, Study of the PPM modulator, Study of the PWM demodulator, Study of the PPM demodulator, Noise effects on the transmission, Sampling frequency and transmission quality.